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Data Compression for a 5x12 Dot Matrix Display

IP.com Disclosure Number: IPCOM000046598D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 102K

Publishing Venue

IBM

Related People

Woodruff, KR: AUTHOR

Abstract

This article describes a technique for encoding common dot patterns to reduce look-up memory size needed for storing character representations. Given the dot matrix character set in Table 1, the first 2 bytes of data for all the characters are contained in the following set. (Image Omitted) The first two bytes of every character can be encoded into a single byte as follows. The first byte in each of the set members is assigned a 3-bit code. The same idea can be applied to the sixth and seventh bytes of each character. The sixth byte of each character is part of a set of 23 bytes given in Table 2. The seventh byte of each character is part of a set of six bytes given in Table 3. The sixth byte bit patterns are assigned binary codes 0 0 0 0 0 through 1 0 1 1 0.

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Data Compression for a 5x12 Dot Matrix Display

This article describes a technique for encoding common dot patterns to reduce look-up memory size needed for storing character representations. Given the dot matrix character set in Table 1, the first 2 bytes of data for all the characters are contained in the following set.

(Image Omitted)

The first two bytes of every character can be encoded into a single byte as follows. The first byte in each of the set members is assigned a 3-bit code. The same idea can be applied to the sixth and seventh bytes of each character. The sixth byte of each character is part of a set of 23 bytes given in Table 2. The seventh byte of each character is part of a set of six bytes given in Table 3. The sixth byte bit patterns are assigned binary codes 0 0 0 0 0 through 1 0 1 1 0. The seventh byte bit patterns are assigned binary codes 0 0 0 through 1 0 1. Thus, the sixth and seventh bytes are encoded into a single byte, 3-bit code concatenated with 5-bit code. Given that the last four bits of each character are always "0", the space required for the look-up table is reduced from 7 bytes per character to 5 bytes per character plus 36 bytes for the common bit patterns.

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